1. Field of the Invention
This invention relates to a blur suppressing device for compensating for any blur in an image caused by a movement of the camera, thereby stabilizing the image.
2. Description of the Related Art
When taking pictures while on a vehicle, ship or airplane, or even while walking one is likely to experience a violent jolting movement which may obscure the image. This is particularly true when the exposure time is long. A jolting movement in such a situation makes it impossible to obtain a picture of satisfactory quality.
When photographing with a single-lens reflex camera equipped with a lens having a long focal length, it is a general practice to attach the camera to a tripod. However, since this limits maneuverability, it is sometimes necessary to hand-hold the camera, thus risking a blurred image. It is well known in the art, that the higher the magnification of a camera lens, the more difficult it is to obtain satisfactory image quality. Recently, a great deal of attention has been directed to this problem.
Various optical image stabilization systems for avoiding such a problem have been proposed. In one well-known system, for example, a bellows, in which a transparent liquid having a predetermined index of refraction is sealed, is provided in front of the photographic lens. The angle defined by the incident and exit planes of this bellows is so controlled that the angle of optical refraction of the wedge defined by this bellows serves to compensate for any change in position caused by jolting of the photographic lens. Japanese Patent Laid-Open Publication No. 61-223819 discloses an example of such a system.
A conversion lens is generally adopted where it is desired that the focal length of the photographic lens be enlarged. There are two systems of arranging such a conversion lens. In one system, the image blur suppressing device is provided in front of the conversion lens, and, in the other, the image blur suppressing device is provided behind the conversion lens or within the photographic lens.
In the case where the blur suppressing device is provided in front of the conversion lens, there is no need to vary the amount of compensation of the blur suppressing device, i.e., the refraction amount of the optical path, in accordance with whether the conversion lens is attached. However, there is the problem that the diameter of the suppressing device has to be large in order to avoid vignetting of the effective photographic luminous flux.
The latter system might be more advantageous in that it allows the diameter of the suppressing device to be smaller than in the former system. However, the amount of compensation effected by the image blur suppressing device when the conversion lens means is attached differs from that when it is not, thus making it impossible to effect blur suppression satisfactorily.